Techniques pattern-forming techniques) in which a fine pattern is formed on top of a substrate, and a lower layer beneath that pattern is then fabricated by conducting etching with this pattern as a mask are widely used in the semiconductor industry for IC fabrication and the like, and are attracting considerable attention.
These types of fine patterns are formed from an organic material, and are formed, for example, using a lithography method or a nanoimprint method or the like.
For example, in the case of a lithography method, a resist pattern is formed using a resist composition that contains a resin component.
These resist compositions include positive resist compositions and negative resist compositions. A coating film formed from a positive resist composition is insoluble in alkali developing solutions prior to exposure, but becomes soluble following exposure. A coating film formed from a negative resist composition is soluble in alkali developing solutions prior to exposure, but becomes insoluble following exposure.
As a result, when a pattern is formed using, for example, a positive resist composition, the positive resist composition is applied to a substrate, and then dried to form a coating film (a resist film). Subsequently, this resist film is selectively exposed, and is then developed in an alkali developing solution, thereby removing the exposed portions that have become soluble in the alkali developing solution, and forming a resist pattern.
Using this resist pattern as a mask, a semiconductor or the like is produced by conducting a step in which the substrate is processed by etching. As the etching either wet etching or dry etching may be used, although dry etching is the more widely used (see patent reference 1).
Because these types of patterns are used as masks, they must exhibit excellent etching resistance.
Furthermore, in the type of pattern-forming techniques described above, a BARC (Bottom Anti-Reflective Coating) method is typically employed in which a BARC film with an anti-reflective function is disposed between the above type of substrate and the coating film used for forming the pattern. As the BARC, an organic film (organic BARC) formed from an organic material such as a film-forming resin is typically used. The organic BARC is usually etched using the pattern (the upper layer pattern) formed on top of the BARC, and is subsequently used, together with the upper layer pattern, as the mask for etching the substrate.
In such cases, because the upper layer pattern is used as the mask for conducting etching of the organic BARC, this upper layer pattern must have greater etching resistance than the organic BARC, or in other words, must exhibit a high etching selectivity ratio relative to the organic BARC.
Conventionally, chemical vapor deposition methods (hereafter also referred to as CVD methods) and SOG (spin-on-glass) methods and the like have been used for forming silica based coating films such as SiO2 films. An SOG method is a method in which, generally, a solution (hereafter also referred to as a SOG solution) prepared by dissolving a silicon compound in an organic solvent is applied and then subjected to a heat treatment, thereby forming a film containing SiO2 as the main component (hereafter also referred to as a SOG coating film) (for example, see patent references 2 to 4).
[Patent Reference 1]
Japanese Unexamined Patent Application, First Publication No. 2003-167346
[Patent Reference 2]
Japanese Examined Patent Application, Second Publication No. Hei 8-3074 (Japanese Unexamined Patent Application, First Publication No. Sho 63-241076)
[Patent Reference 3]
Japanese Patent (Granted) Publication No. 2,739,902 (Japanese Unexamined Patent Application, First Publication No. Hei 7-97548)
[Patent Reference 4]
Japanese Patent (Granted) Publication No. 3,228,714 (Japanese Unexamined Patent Application, First Publication No. Hei 11-251310)